A hybrid powertrain improves a vehicle's fuel economy relative to a conventional powertrain via the selective use of different torque generating devices. The various torque generating devices of a hybrid powertrain, which are also referred to as torque actuators, are selected by a hybrid controller based on present range state torque requirements. Typical hybrid torque actuators include an internal combustion engine and one or more electric motor/generators. Output torque generated by the torque actuators is ultimately transferred through one or more gear sets of a transmission to an output member, which is connected in turn to the drive axle(s) of the vehicle.
A strong hybrid driveline system controls multiple torque actuators in a closed loop using proportional-integral (PI) or proportional-integral-derivative (PID) control logic so as to achieve a desired target value, such as a desired engine or clutch rotational torque, speed, or a desired level of driveline damping. However, even using PI or PID control logic, it may be difficult to maintain smooth closed-loop control during certain transitional vehicle events, for instance during a hybrid state transition or a control gain reduction event.